Recovery of wool from mixed woolcellulose acetate textiles



Patented Jan. 29, 1946 RECOVERY OF WOOL FROM MIXED WOOL- CELLULOSEACETATE TEXTILES George W. Seymour and George C. Ward, Cumberland, Md.,assignors to Celanese Corporation of America, a corporation of DelawareNo Drawing. Application March 10, 1944, Serial No. 525,953

3 Claims. (01. 8 -1 10) This invention relates to the treatment of mixedtextile materials and relates more particularly to the treatment oftextile materials comprising a mixture of wool and organic ester ofcellulose fibers, whereby the wool fibers may be removed in aneconomical and convenient manner.

Other objects of this invention will appear hereinafter from thefollowing detailed description.

In textile operations involving the use of wool and cellulose acetate orother organic esters of cellulose yarns, there is produced a certainproportion of Waste consisting of a mixture of wool and celluloseacetate or other organic ester of cellulose fibers. Such mixtures may bedyed in a solid shade but the dyed mixture is of value only where thereis a need for a textile material containing the particular fibers in theprecise proportions present in the waste. Where, for example, a mixtureof wool and cellulose acetate fibers is available and only therelatively valuable wool in the mixture is desired, the only practicalsolution tothe recovery of the wool is to remove the non-woolenmaterials. Mixtures of wool and cellulose acetate or other organic esterof cellulose, are however, not amenable to the usual separation orcarbonization treatments such as those employed for removing cellulosematerials from wool. Such treatments have no effect on cellulose estermaterials since the cellulose esters difier substantially from cellulosematerials in their physical and chemical properties. Not only must aprocess for separating wool and cellulose acetate materials be effectiveand ecomay be recovered from a fiber mixture comprising wool and fibershaving a basis of cellulose acetate, or other organic ester ofcellulose, by

impregnating the fibers with an aqueous solution of an organic swellingagent for the cellulose acetate fibers containing an inorganiccarbonizing agent, drying the fibers, and then baking the dried fibersat elevated temperature. The swelling agent causes the cellulose acetatefibers to swell and enables the inorganic carbonizing agent to penetratethe cellulose acetate fibers and, during the baking operation, thecarbonizing agent effects a carbonization of the cellulose acetatefibers. Following carbonization, the fibers are washed and the woolfibers which were originally present are recovered in a satisfactorycondition and in full possession of their original textilecharacteristics and properties.

Suitable swelling agents which may be employed in treating the fibermixture are, for example, ethyl alcohol, acetone, isopropyl alcohol,butyl alcohol, methyl ethyl ketone and ethyl lactate. Satisfactoryswelling action may be eifected when the swelling agent is present inthe aqueous solution in concentrations of 5 to 50% by weight. While allof these swelling agents are suitable, we preferably employ ethylalcohol, and

optimum results are achieved with aqueous solutions containing from 15to 35% of this alcohol.

Various inorganic carbonizing agents having a carbonizing action oncellulose acetate materials may be employed. Preferably, we employinorganic mineral acids such as sulfuric acid, hydrochloric acid orphosphoric acid, e. g. orthophosphoric acid, but inorganic agents suchas aluminum chloride, which yields hydrochloric acid by hydrolysis andon heating, may also be employed. When employing sulfuric acid,concentrations of 4 to 8% by weight of the acid in the impregnatingsolution containing the organic swelling agent are suitable.

' The penetration of the cellulose acetate fibers by the carbonizingagent, is effected by maintaining the fiber mixture in the aqueoussolution of swelling agent containing the carbonizing agent for 2 to 20minutes at 20 to 50 C. The fiber mixture isthen removed from the aqueoussolution, dried and baked for 5 to 30 minutes at to C. The celluloseacetate fibers are carbonized during the baking operation and, afterwashing with water, the wool fibers in the initial fiber mixture arerecovered in unchanged form and in full possession of their originalvaluable textile properties.

Furthermore, we have found, for example, that when employing aqueoussolutions containing ethyl alcohol as the swelling agent and sulfuricacid as the carbonizing agent, a substantial reduction in the amount ofswelling agent employed may be effected if a hydrohalic carbonizingacid, e. g.hydrochloric acid, is also added to the aqueous impregnatingsolution. Thus, when employamples are given:

ing from 2 to 5% by weight of hydrochloric acid in the solution, wemay-employ a decreased amount of ethyl alcohol, say. 5 to 15%. in thewaste materials comprising wool and cellulose acetate materials torecover wool fibers free of said materials, mixtures of wool, celluloseacetate and cellulose fibers are commonly encountered in commercialoperation and the examples'will be directed to the recovery of woolfibers from such mixtures.

In order further to illustrate our invention but without being limitedthereto, the following ex- Emamplc I A mixture of textile fiberscomprising 65% by covered wool fibers retain their original textileproperties and may be employed-again for all textile applications.

Example [I A mixture of textile fibers cm nsmg 65% by weight of wool,28% of cellulose acetate fibers, and 7% of cellulosic fibers is immersedin' an aqueous bath comprising 25% by weight of ethyl many novel anddecorative effects may be obtained by weaving a fabric of wool andcellulose acetate yarns orfibers and then removing all of the non-woolenfibers.

While the foregoing description and examples are directed primarily tothe treatment of mixtures of wool with cellulose acetate, which mixturemay contain cellulose fibers, other organic esters of cellulose suchas,for example, cellulose propionate, cellulose butyrate, and mixed estersof cellulose such as cellulose acetate-propicnate and celluloseacetate-butyrate, may be removed in like manner from textile materialsin which they are present together with wool, and the latter recoveredin unimpaired form.

It is to beunderstood that the foregoing detailed description is givenmerely by way of innstration and that many variations may be madetherein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by LettersPatent is:

1. Process for the recovery of wool from mixed textile materialscontaining wool and cellulose acetate fibers, which comprises immersingsaid mixture of fibers in an aqueous bath containing from 5 to 15% ofethyl alcohol, from 4 to 8% of sulfuric acid and from 2' to 5% ofhydrochloric acid until penetration of the cellulose acetate fibers iseffected, drying thefiber mixture, and

. baking the dried fibers at elevated temperature,

alcohol and 6% of sulfuric acid. The fibers are maintained therein for15 minutes at 30 C. and

are then removed from the bath, dried, and baked at 110 C. for 10minutes. After washing, the fibers remaining comprise pure wool fibersfree of all cellulose acetate and cellulosic fibers. The recovered woolfibers possess their usual textile properties and may be employed againin the preparation of woolen and worsted materials.

It is to be understood, of course, that our novel process maybe appliedto any textile material. suchas, for example, a fabric made of orcontaining a mixture of textile fibers comprising wool and celluloseacetate or wool, cellulose acetate and cellulosic fibers and, aftertreatment, a pure woolen fabric may be obtained. In this manner,

whereby the cellulos acetate fibers are carbonized and wool fibersfreeof other textile materials are obtained.

2. Process for the recovery of wool from mixed textile materialscontaining wool and cellulose acetate fibers, which comprises immersingsaid textile materials containing wool and cellulose acetate fibers,which comprises immersing said mixture of fibers in an aqueous bathcontaining from 5 to 15% of ethyl alcohol, from etc 8% of sulfuric acidand from 2 to 5% of hydrochloric acid for 2 to 20 minutes at 20 to 500., drying the fiber mixture, and baking the dried fibers for 5 to 30minutes at to (7., whereby the cellulose acetate fibers are carbonizedand wool fibers free of other textile materials are obtained.

GEORGE W. SEYMOUR. GEORGE C. WARD.

